; ; jcqntmmx.asm - sample data conversion and quantization (MMX) ; ; Copyright 2009 Pierre Ossman for Cendio AB ; ; Based on ; x86 SIMD extension for IJG JPEG library ; Copyright (C) 1999-2006, MIYASAKA Masaru. ; For conditions of distribution and use, see copyright notice in jsimdext.inc ; ; This file should be assembled with NASM (Netwide Assembler), ; can *not* be assembled with Microsoft's MASM or any compatible ; assembler (including Borland's Turbo Assembler). ; NASM is available from http://nasm.sourceforge.net/ or ; http://sourceforge.net/project/showfiles.php?group_id=6208 ; ; [TAB8] %include "jsimdext.inc" %include "jdct.inc" ; -------------------------------------------------------------------------- SECTION SEG_TEXT BITS 32 ; ; Load data into workspace, applying unsigned->signed conversion ; ; GLOBAL(void) ; jsimd_convsamp_mmx (JSAMPARRAY sample_data, JDIMENSION start_col, ; DCTELEM * workspace); ; %define sample_data ebp+8 ; JSAMPARRAY sample_data %define start_col ebp+12 ; JDIMENSION start_col %define workspace ebp+16 ; DCTELEM * workspace align 16 global EXTN(jsimd_convsamp_mmx) EXTN(jsimd_convsamp_mmx): push ebp mov ebp,esp push ebx ; push ecx ; need not be preserved ; push edx ; need not be preserved push esi push edi pxor mm6,mm6 ; mm6=(all 0's) pcmpeqw mm7,mm7 psllw mm7,7 ; mm7={0xFF80 0xFF80 0xFF80 0xFF80} mov esi, JSAMPARRAY [sample_data] ; (JSAMPROW *) mov eax, JDIMENSION [start_col] mov edi, POINTER [workspace] ; (DCTELEM *) mov ecx, DCTSIZE/4 alignx 16,7 .convloop: mov ebx, JSAMPROW [esi+0*SIZEOF_JSAMPROW] ; (JSAMPLE *) mov edx, JSAMPROW [esi+1*SIZEOF_JSAMPROW] ; (JSAMPLE *) movq mm0, MMWORD [ebx+eax*SIZEOF_JSAMPLE] ; mm0=(01234567) movq mm1, MMWORD [edx+eax*SIZEOF_JSAMPLE] ; mm1=(89ABCDEF) mov ebx, JSAMPROW [esi+2*SIZEOF_JSAMPROW] ; (JSAMPLE *) mov edx, JSAMPROW [esi+3*SIZEOF_JSAMPROW] ; (JSAMPLE *) movq mm2, MMWORD [ebx+eax*SIZEOF_JSAMPLE] ; mm2=(GHIJKLMN) movq mm3, MMWORD [edx+eax*SIZEOF_JSAMPLE] ; mm3=(OPQRSTUV) movq mm4,mm0 punpcklbw mm0,mm6 ; mm0=(0123) punpckhbw mm4,mm6 ; mm4=(4567) movq mm5,mm1 punpcklbw mm1,mm6 ; mm1=(89AB) punpckhbw mm5,mm6 ; mm5=(CDEF) paddw mm0,mm7 paddw mm4,mm7 paddw mm1,mm7 paddw mm5,mm7 movq MMWORD [MMBLOCK(0,0,edi,SIZEOF_DCTELEM)], mm0 movq MMWORD [MMBLOCK(0,1,edi,SIZEOF_DCTELEM)], mm4 movq MMWORD [MMBLOCK(1,0,edi,SIZEOF_DCTELEM)], mm1 movq MMWORD [MMBLOCK(1,1,edi,SIZEOF_DCTELEM)], mm5 movq mm0,mm2 punpcklbw mm2,mm6 ; mm2=(GHIJ) punpckhbw mm0,mm6 ; mm0=(KLMN) movq mm4,mm3 punpcklbw mm3,mm6 ; mm3=(OPQR) punpckhbw mm4,mm6 ; mm4=(STUV) paddw mm2,mm7 paddw mm0,mm7 paddw mm3,mm7 paddw mm4,mm7 movq MMWORD [MMBLOCK(2,0,edi,SIZEOF_DCTELEM)], mm2 movq MMWORD [MMBLOCK(2,1,edi,SIZEOF_DCTELEM)], mm0 movq MMWORD [MMBLOCK(3,0,edi,SIZEOF_DCTELEM)], mm3 movq MMWORD [MMBLOCK(3,1,edi,SIZEOF_DCTELEM)], mm4 add esi, byte 4*SIZEOF_JSAMPROW add edi, byte 4*DCTSIZE*SIZEOF_DCTELEM dec ecx jnz short .convloop emms ; empty MMX state pop edi pop esi ; pop edx ; need not be preserved ; pop ecx ; need not be preserved pop ebx pop ebp ret ; -------------------------------------------------------------------------- ; ; Quantize/descale the coefficients, and store into coef_block ; ; This implementation is based on an algorithm described in ; "How to optimize for the Pentium family of microprocessors" ; (http://www.agner.org/assem/). ; ; GLOBAL(void) ; jsimd_quantize_mmx (JCOEFPTR coef_block, DCTELEM * divisors, ; DCTELEM * workspace); ; %define RECIPROCAL(m,n,b) MMBLOCK(DCTSIZE*0+(m),(n),(b),SIZEOF_DCTELEM) %define CORRECTION(m,n,b) MMBLOCK(DCTSIZE*1+(m),(n),(b),SIZEOF_DCTELEM) %define SCALE(m,n,b) MMBLOCK(DCTSIZE*2+(m),(n),(b),SIZEOF_DCTELEM) %define SHIFT(m,n,b) MMBLOCK(DCTSIZE*3+(m),(n),(b),SIZEOF_DCTELEM) %define coef_block ebp+8 ; JCOEFPTR coef_block %define divisors ebp+12 ; DCTELEM * divisors %define workspace ebp+16 ; DCTELEM * workspace align 16 global EXTN(jsimd_quantize_mmx) EXTN(jsimd_quantize_mmx): push ebp mov ebp,esp ; push ebx ; unused ; push ecx ; unused ; push edx ; need not be preserved push esi push edi mov esi, POINTER [workspace] mov edx, POINTER [divisors] mov edi, JCOEFPTR [coef_block] mov ah, 2 alignx 16,7 .quantloop1: mov al, DCTSIZE2/8/2 alignx 16,7 .quantloop2: movq mm2, MMWORD [MMBLOCK(0,0,esi,SIZEOF_DCTELEM)] movq mm3, MMWORD [MMBLOCK(0,1,esi,SIZEOF_DCTELEM)] movq mm0,mm2 movq mm1,mm3 psraw mm2,(WORD_BIT-1) ; -1 if value < 0, 0 otherwise psraw mm3,(WORD_BIT-1) pxor mm0,mm2 ; val = -val pxor mm1,mm3 psubw mm0,mm2 psubw mm1,mm3 ; ; MMX is an annoyingly crappy instruction set. It has two ; misfeatures that are causing problems here: ; ; - All multiplications are signed. ; ; - The second operand for the shifts is not treated as packed. ; ; ; We work around the first problem by implementing this algorithm: ; ; unsigned long unsigned_multiply(unsigned short x, unsigned short y) ; { ; enum { SHORT_BIT = 16 }; ; signed short sx = (signed short) x; ; signed short sy = (signed short) y; ; signed long sz; ; ; sz = (long) sx * (long) sy; /* signed multiply */ ; ; if (sx < 0) sz += (long) sy << SHORT_BIT; ; if (sy < 0) sz += (long) sx << SHORT_BIT; ; ; return (unsigned long) sz; ; } ; ; (note that a negative sx adds _sy_ and vice versa) ; ; For the second problem, we replace the shift by a multiplication. ; Unfortunately that means we have to deal with the signed issue again. ; paddw mm0, MMWORD [CORRECTION(0,0,edx)] ; correction + roundfactor paddw mm1, MMWORD [CORRECTION(0,1,edx)] movq mm4,mm0 ; store current value for later movq mm5,mm1 pmulhw mm0, MMWORD [RECIPROCAL(0,0,edx)] ; reciprocal pmulhw mm1, MMWORD [RECIPROCAL(0,1,edx)] paddw mm0,mm4 ; reciprocal is always negative (MSB=1), paddw mm1,mm5 ; so we always need to add the initial value ; (input value is never negative as we ; inverted it at the start of this routine) ; here it gets a bit tricky as both scale ; and mm0/mm1 can be negative movq mm6, MMWORD [SCALE(0,0,edx)] ; scale movq mm7, MMWORD [SCALE(0,1,edx)] movq mm4,mm0 movq mm5,mm1 pmulhw mm0,mm6 pmulhw mm1,mm7 psraw mm6,(WORD_BIT-1) ; determine if scale is negative psraw mm7,(WORD_BIT-1) pand mm6,mm4 ; and add input if it is pand mm7,mm5 paddw mm0,mm6 paddw mm1,mm7 psraw mm4,(WORD_BIT-1) ; then check if negative input psraw mm5,(WORD_BIT-1) pand mm4, MMWORD [SCALE(0,0,edx)] ; and add scale if it is pand mm5, MMWORD [SCALE(0,1,edx)] paddw mm0,mm4 paddw mm1,mm5 pxor mm0,mm2 ; val = -val pxor mm1,mm3 psubw mm0,mm2 psubw mm1,mm3 movq MMWORD [MMBLOCK(0,0,edi,SIZEOF_DCTELEM)], mm0 movq MMWORD [MMBLOCK(0,1,edi,SIZEOF_DCTELEM)], mm1 add esi, byte 8*SIZEOF_DCTELEM add edx, byte 8*SIZEOF_DCTELEM add edi, byte 8*SIZEOF_JCOEF dec al jnz near .quantloop2 dec ah jnz near .quantloop1 ; to avoid branch misprediction emms ; empty MMX state pop edi pop esi ; pop edx ; need not be preserved ; pop ecx ; unused ; pop ebx ; unused pop ebp ret ; For some reason, the OS X linker does not honor the request to align the ; segment unless we do this. align 16